Further development and studies of nuclear reactors call for studies of reaction rates in heterogeneous fast reactors. Studies include the measurement of neutron flux densities in various positions across a reactor core such as by inserting a nuclear reactor fuel material at various positions in the core and measuring the activation induced in these fuel materials. Some of these studies involve or require the use of actinide foils at elevated temperatures, the actinide fuel material in some cases being surrounded by a cladding material to prevent surface oxidation of the actinide fuel material during the tests.
Applied physics studies of reaction rates and measurements of neutron flux densities in reactor cores, such as are being conducted in the variable - temperature rodded - zone experiments in the Zero Power Reactor experiments at Argonne National Laboratory, a description of which can be found in Argonne National Laboratory Report ANL-7639 and other subsequent reports, require the use of high-temperature activation-measurement foils. It is desirable that these high-temperature activation-measurement foils be produced from nuclear reactor fuel materials. However, a problem is encountered in these experiments when plutonium is the desired fuel material, as plutonium has a melting point of about 640.degree. C. which is below the temperatures reached during these experiments. While it is known that the melting point of plutonium fuel material can be increased by alloying the plutonium with other metals or with a combination of other metals in various proportions, other requirements for the production of the fuel alloy foil materials for use in these experiments are as equally important as an increase in the melting point. A first requirement is that the plutonium content be at least 90 w/o (weight percent) in order to insure consistent and accurate measurements. Since the material is to be used as a thin fuel foil, it is very essential that the plutonium alloy be castable and rollable to very thin foils. It is also necessary that the fuel foil be compatible with the cladding material jacket which surrounds the foil and that the foil remain compatible with the cladding material when repeatedly cycled to temperatures in excess of 650.degree. C. If any alloying would occur between the foil and the cladding material during the repeated cycling to the elevated temperatures, the accuracy of the activation measurements would be destroyed, and any tendency for such alloying or any incompatibility is therefore impermissible.
Therefore, it is an object of the present invention to provide a nuclear reactor fuel alloy of a minimum of 90 w/o plutonium, which alloy is castable and rollable to very thin foils.
It is another object of the present invention to provide a nuclear reactor fuel alloy whose melting point is significantly greater than the melting point of plutonium.
It is another object of the present invention to provide a nuclear reactor fuel alloy foil which is compatible with cladding material at elevated temperatures.
Another object of the present invention is to provide a high-temperature activation-measurement foil containing at least 90 w/o plutonium, which foil is compatible with cladding material when repeatedly cycled to temperatures above 650.degree. C.